//基本类型
var a = "yj";
var b = 12;
var c = true;
var d = 34; //不安全
console.log(d.toFixed(2));
var e = 45; //安全
if (typeof e === "number") {
    console.log(e.toFixed(2));
}
var f = null;
var g = undefined;
//void,never
function add() {
    console.log("12");
}
function add1() {
    throw new Error("Error");
}
//引用类型
var arr = [12, 4, 5];
var arr1 = [2, 4, "skd", true];
var arr2 = ["sad", "fyj"];
//object
var person = {
    name: "sa",
    age: 18
};
var p1 = {
    name: "dja",
    age: 19
};
var p2 = {
    name: "bod",
    age: 20
};
